A variety of window treatment products have been developed in recent years including curtains, roller blinds, venetian blinds and expandable-collapsible articles. One type of expandable-collapsible product is a zig-zag or accordion-folded article comprising a series of interconnected pleats such as disclosed, for example, in U.S. Pat. Nos. 4,181,070; 3,921,432 and 4,012,932. Another type of construction is the so-called "honeycomb" or cellular structure wherein selected folded portions of one or more sheet materials are interconnected by adhesive or other means of attachment to form side-by-side elongated hollow channels. Patents illustrative of honeycomb-type expandable-collapsible products include U.S. Pat. Nos. 4,603,072; 4,631,108; 4,685,986; 4,631,217; 4,676,855; 4,677,012; and 4,677,013.
A more recent development has involved an attempt to combine aspects of expandable-collapsible articles with a construction resembling a venetian blind. One example of this construction is disclosed in U.S. Pat. No. 5,287,908 directed to a window assembly which includes first and second generally parallel, spaced, longitudinally extending sheer fabrics which form the inner and outer sides of the window covering. A plurality of longitudinally spaced sections of fabric or "vanes" are affixed between the first and second sheer fabrics to form the completed assembly. Preferably, the vanes are oriented parallel to one another and extend transversely across the width of the fabric sheets from edge to edge.
The sheer fabrics are typically constructed of a translucent or transparent material such as fabric, non-woven fabric or sheets of plastic material, and the vanes are preferably opaque or semi-opaque, By adjusting the relative positions of the sheer fabrics, the vanes are caused to tilt relative to one another in a manner similar to the slats of a venetian blind. In an "open" position, the vanes are oriented parallel to one another and generally perpendicular to each of the two sheets so that only an edge of each vane can be seen when viewing the sheets from the front or back of the window covering. When one of the sheets or sheer fabrics is moved relative to the other, the vanes tilt to a closed position substantially parallel to the sheer fabrics and overlap or at least abut one another in the transverse direction. In this position, the entire window covering can be wound about a wind-up roll at the top of the window covering assembly to completely expose the window.
One problem with window coverings of the type disclosed in U.S. Pat. No. 5,287,908 is that a difficult fabrication problem is presented in affixing the vanes to the sheer fabrics. Each transversely extending edge of each vane must be separately glued or otherwise affixed to the adjacent sheer fabric in order to form a connection therebetween. Given the flimsy nature of the sheer fabrics and the material forming the vanes, it is difficult to efficiently and rapidly align the transverse edges of each vane with respect to the sheer fabrics, apply a bead of glue or other means of connection thereto and then press the fabric sheets and vanes together to achieve a bond therebetween. Consequently, the rate at which such articles can be produced is relatively low, and the cost of the finished article is high.